Explain Terzaghi's bearing capacity equation and its components.

Terzaghi's equation for ultimate bearing capacity: qu = cNc + qNq + 0.5*gamma*B*Ngamma, where c = cohesion, q = overburden pressure (gamma*D), B = foundation width, gamma = unit weight, and Nc, Nq, Ngamma are bearing capacity factors depending on friction angle phi. First term represents cohesion contribution, second is surcharge (depth) contribution, third is foundation width effect. Shape factors are applied for rectangular/circular footings. This equation assumes general shear failure and homogeneous soil.